(JNS.org) The head of the World Jewish Congress has called on the Swedish government to step up security at Jewish sites around Stockholm following a recent anti-Semitic incident.

On Monday, anti-Semitic graffiti was found on a central Stockholm school that holds classes for Jewish students. The graffiti includes swastikas as well as the phrases “Jewish swine” and “disgusting Jews.” The vandals also spray painted the number “1488,” which symbolizes the Nazi slogan “Heil Hitler,” Sweden’s English-language daily The Local reported. Anti-Semitic graffiti was also found at other nearby schools.

“With an upsurge in Sweden of violent and anti-Semitic behavior linked to political extremism, the authorities must step up protection around Jewish sites,” World Jewish Congress President Ronald S. Lauder said.

Lena Posner-Korosi, president of the Council of Swedish Jewish Communities, said that the Swedish government has expressed concern about the incident and has been in touch with police.